Polyvinyl butyral is widely used in combination with one or more layers of glass to provide a composite which is resistant to shattering. The polyvinyl butyral typically contains a plasticizer to provide a balance of mechanical properties satisfactory for subsequent handling and performance requirements. It has been found that while certain plasticizers perform satisfactorily in combination with polyvinyl butyral, high concentrations of the plasticizer are generally necessary for satisfactory handling characteristics. In addition, many known plasticizers are incompatible with polyvinyl butyral outside of limited ranges of hydroxyl content.
The instant invention provides a plastic composition comprising polyvinyl butyral and, in compatible admixture therewith, a plasticizer comprising at least about 10 weight percent tetraethyleneglycol di-n-heptanoate of the general formula ##STR1##